}

  Optional() {}

  /**
   * Returns {@code true} if this holder contains a (non-null) instance.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
   */
  public abstract boolean isPresent();

  /**
   * Returns the contained instance, which must be present. If the instance might be absent, use

 * the reference is "absent"); it is never said to "contain {@code null}".
 *
 * <p>A non-null {@code Optional<T>} reference can be used as a replacement for a nullable {@code T}
 * reference. It allows you to represent "a {@code T} that must be present" and a "a {@code T} that
 * might be absent" as two distinct types in your program, which can aid clarity.
 *
 * <p>Some uses of this class include
 *
 * <ul>

// out. It stores whether an element with the tag was found in outPresent,
// unless outPresent is nil. It reports whether the read was successful.
func (s *String) ReadOptionalASN1(out *String, outPresent *bool, tag asn1.Tag) bool {
	present := s.PeekASN1Tag(tag)
	if outPresent != nil {
		*outPresent = present
	}
	if present && !s.ReadASN1(out, tag) {
		return false
	}
	return true
}

		}
		return ParseSecretKey(s)
	}
}

// IsPresent reports whether a KMS configuration is present.
// It returns an error if multiple KMS configurations are
// present or if one configuration is incomplete.
func IsPresent() (bool, error) {
	// isPresent reports whether at least one of the
	// given env. variables is present.
	isPresent := func(vars ...string) bool {
		for _, v := range vars {

    /**
     * Returns {@code true} if there is a value present, otherwise {@code false}.
     *
     * @return {@code true} if there is a value present, otherwise {@code false}
     */
    boolean isPresent();

    /**
     * Returns a {@link Provider} whose value is the value of this provider, if present, otherwise the
     * given default value.
     *

            if (!wildcardType.getExtendedType().isPresent() && !wildcardType.getSuperType().isPresent()) {
                typeMetaData.setWildcard();
            } else {
                wildcardType.getExtendedType().ifPresent(referenceType -> typeMetaData.setUpperBounds(extractTypeName(referenceType)));
                wildcardType.getSuperType().ifPresent(referenceType -> typeMetaData.setLowerBounds(extractTypeName(referenceType)));

        expect:
        property.present
        property.get() == 13

        when:
        property.convention((Number) null)
        property.get()

        then:
        def e = thrown(MissingValueException)
        e.message == "Cannot query the value of ${displayName} because it has no value available."

        and:
        !property.present
    }

        ex.cause.message == "Failing constructor"

        and:
        provider.isPresent()

        and:
        container.withType(DefaultTask).named("task").isPresent()

        and:
        container.named("task").isPresent()

        when:
        container.findByName("task")

        then:
        def ex2 = thrown(GradleException)

 * </p>
 *     <ul>
 *         <li>{@link SingleElement} to represent a single element addition
 *         <li>{@link ElementFromProvider} to represent a single element added as a provider
 *         <li>{@link ElementsFromArray} to represent a single element added as an array</li>
 *         <li>{@link ElementsFromCollection} to represent a batch of elements added (or set wholesale) as an <code>Iterable</code>

        Optional<Long> sizeIfKnown = source.sizeIfKnown();
        if (!sizeIfKnown.isPresent()) {
          return Optional.absent();
        }
        result += sizeIfKnown.get();
        if (result < 0) {
          // Overflow (or one or more sources that returned a negative size, but all bets are off in
          // that case)
          // Can't represent anything higher, and realistically there probably isn't anything that